The Language of Argument

3 3 4

C H A P T E R 1 7 ■ R e f u t a t i o n

Counterexamples

The first main way to attack an argument is to challenge one of its premises.

We can argue that there is no good reason to accept a particular premise as

true, asking, for example, “How do you know that?” If the premise is not

justified, then the argument fails to justify its conclusion. More strongly, we

can argue that the premise is actually false. In this second case, we refute an

argument by refuting one of its premises.

One common way to refute a premise by showing that it is false is by pro-

ducing a counterexample. Counterexamples are typically aimed at universal

claims. This is true because a single contrary instance will show that a uni-

versal claim is false. If someone claims that all snakes lay eggs, then pointing

out that rattlesnakes bear their young alive is sufficient to refute this univer-

sal claim. If the person retreats to the weaker claim that most snakes lay eggs,

the guarding term makes it much harder to refute the claim. A single exam-

ple of a snake that bears its young alive is not enough to refute this claim; we

would have to show that a majority of snakes do not lay eggs. Here, instead

of trying to refute the statement, we may ask the person to produce his argu-

ment on behalf of it. We can then attack this argument. Finally, if the person

retreats to the very weak claim that at least some snakes lay eggs, then this

statement becomes very difficult to refute. Even if it were false (which it is

not), to show this we would have to check every single snake and establish

that it does not lay eggs. So, as a rough-and-ready rule, we can say that the

stronger a statement is, the more subject it is to refutation; the weaker it is,

the less subject it is to refutation.

When a universal claim is refuted by a single case, that case is a coun-

terexample to the universal claim. The pattern of reasoning is perfectly sim-

ple: To refute a claim that everything of a certain kind has a certain feature,

we need find only one thing of that kind lacking that feature. In response to

a counterexample, many people just repeat the misleading saying, “That’s

the exception that proves the rule.” What most people do not realize is that

“proves” originally meant “tests,” so all this saying means is that an appar-

ent exception can be used to test a rule or a universal claim. When the excep-

tion is a true counterexample, the universal claim fails the test.

There are only two ways to defend a universal claim against a pur-

ported counterexample. Because the universal claim says that all things

Is refuting an argument the same as justifying a belief that its conclusion is

false? Is it the same as justifying a belief that the argument is invalid or weak?

Why or why not?

Discussion Question

97364_ch17_ptg01_333-350.indd 334 15/11/13 11:12 AM

some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materiallyCopyright 201^3 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights,

affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.